1. Field of the Invention
The present invention generally relates to audio/video systems, and more particularly, to an audio/video system capable of introducing variable amounts of delay into a signal path so as to properly synchronize audio and video signals.
2. Background Information
Audio/video systems, such as digital television signal receivers, often employ various types of video processing, such as MPEG decoding, that introduce processing delay in a video signal path. In order to synchronize the accompanying audio signal path to the video signal path, the audio signal path must undergo a similar delay. If no such delay is added to the audio signal path, an undesirable synchronization problem occurs in that the audio and video outputs are not synchronized during program viewing. That is, a noticeable “lip sync” problem may occur during program viewing if a proper amount of delay is not added to the audio signal path.
One approach for introducing delay in a signal path involves using a number of serially arranged flip-flops or other delay devices corresponding to the desired delay. This approach, however, is limited in that the delay is typically fixed for a given application. Accordingly, this approach fails to provide a range of different delays. Moreover, such an approach is not necessarily suitable for implementing large delays, especially in consumer electronics applications where additional hardware and the associated costs are strongly avoided.
Different signal processing schemes may introduce different amounts of delay in the video signal path, thus requiring corresponding different amounts of delay in the audio signal path. For example, the delay introduced when decoding a video format on one channel or source may be different from the delay introduced when decoding another video format on another channel or source. Moreover, the difference between the two delays may be large, thus requiring a large range of delays to be added to the audio signal path.
Accordingly, there is a need for a delay implementation technique which avoids the foregoing problems and thereby provides a large delay range without significantly increasing hardware requirements. The present invention addresses these and other problems.